<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      const arr = ["jack", "li", "ros", "e", "f"];
      const r = arr.findIndex(function (v) {
        console.log(v);
        if (v.length === 3) {
          return true;
        }
      });

      console.log("输出", r); //2
    </script>
  </body>
</html>
